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TREATMENT OF MIDLINE
DISCREPANCIES AND SKELETAL
ASYMMETRIES

INDIAN DENTAL ACADEMY
Leader in continuing dental education
w...
INTRODUCTION
Midline coordination and relative symmetry
are basic to an appreciation of facial harmony
and balance.
Althou...
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Stedman’s Medical Dictionary defines
symmetry as “equality or correspondence
in form of parts distributed around ...
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Mammals have marked asymmetry as to the
placement of the viscera in the body cavity.
Also functional as well as m...
 Each

human being a unique individual.
 Variations in the size, shape and relationship
of the dental, skeletal and soft...
Asymmetry in craniofacial areas can be
recognized as differences in the size or
relationship of the two sides of the
face....


Peck and Peck evaluated bilateral facial
symmetry in 52 “exceptionally well-balanced”
white adults and observed that th...
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An overall asymmetry was found in most of the
children with the left side being larger.
The cranial base, and ma...
 Results

from a study by Miller et al
indicate that the maxillary midline is
situated in the exact middle of the
mouth (...


Midline correction should be undertaken
from the initiation of treatment and once
all midlines are coordinated they sho...
Careful attention to midline coordination and
attendant facial symmetry can aid the
practitioner in achieving the followin...
Etiology of midline
discrepancies and Asymmetry
 Includes

a) Genetic or congenital malformations
e.g. hemifacial microso...
d. Epigenetic factors; and acquired
factors, for example, infections or
pathology
Facial asymmetries can be
classified bas...
 Mandibulofacial

asymmetries have
a postnatal expression.
 The causes are  Tumors in the TMJ region
 Condylar hyperpl...
 Inflammatory

arthritic disease

 Ankylosis
 Intra-articular

disorders with an
associated arthrosis
 Condylar fractu...
Other factors  Intra-uterine

pressure during
pregnancy and significant pressure in
the birth canal during parturition ca...
Localized factors
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Early loss of a deciduous tooth
Rotation of the entire dental arch and its
supporti...
 Lundstrom

stated that asymmetry can
be genetic or nongenetic in origin
and is usually a combination of both.
 Some rig...
Facial photographs of a patient with hemifacial
microsomia. The discrepancies involve one side of the
face only and includ...
Asymmetry of Face due to
fracture of TMJ

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Intrauterine moulding resulting in
midface deficiency

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Deformation of second branchial arch
with corresponding malformations

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Facial asymmetry due to
missing masseter muscle

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Hemimandibular
hypertrophy

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According to Lundstrom, asymmetry can
also be described as qualitative (all or
none) or quantitative.
Examples ...
Skeletal asymmetries-classification
Obwegeser classification as described in the
Journal of Maxillofacial Surgery in 1986....
Hemimandibular elongation
 Can

occur as elongation either of the
condyle or ramus in the vertical
plane or the mandibula...
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Features
Mandible deviates to the opposite side of the
deformity
Exhibits flattening of the gonial angle on the...
Mandibular elongation tends to stop
when body or facial growth stops as it
follows more of a somatic growth
curve.
 Prese...
Hemimandibular hyperplasia
 Recognized

by entire half of the
mandible being enlarged.
 Features
 Mandibular lower bord...
 Hyperplasia,

tends to grow longer
exhibiting “latent” growth.
 The midline usually deviates to the
same side as the de...
 Hemimandibular

hyperplasia, however,
is just about always overgrowth as in
Angle Class III malocclusion that
results fr...
Structural classification of
dentofacial asymmetries
a. Dental asymmetries: These can be
due to: local factors such as ear...
Teeth in the same morphological
class tend to have the same
direction of asymmetry.
 Asymmetry tends to be greater for
th...
b.Skeletal asymmetries: The deviation may
involve one bone such as the maxilla or
mandible , or it may involve a number of...
Patient with a skeletal mandibular asymmetry. The mandibular
dental midline was shifted 7.0 mm to the left of the maxillar...
Post treatment photographs. Despite correction of the
skeletal asymmetry some soft tissue facial asymmetry
remained. Note ...
d.

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Functional asymmetries: These can
result from the mandible being deflected
laterally or antero-posteriorly, if occl...
Intraoral view of a patient in centric relation. Note the shift in
the lower midline. Posterior occlusion was cusp on cusp...
CLASSIFICATION -According to
Steenbergen and Nanda
 Dental asymmetries can be divided into four
groups:
1. Diverging occl...
DIAGNOSIS
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1.

A: Clincial examination
Evaluation of the dental midlines:
includes an evaluation of the dental
midlines i...
Location of midline


Various points (landmarks) can be identified from the
frontal head film, the frontal photographs, o...
A

symmetrical head can produce an
asymmetrical posteroanterior film if the head
is improperly oriented
 Any rotation of...
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 Connecting

the points-soft tissue
nasion, subnasale and soft tissue
pogonion- also locates midline
 Can give variable ...
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 Bisecting

a line that connects
corresponding bilateral landmarks may
be invalid since absolute symmetry
between right a...
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Another method for determining the
facial midline is to establish a
horizontal plane from skeletal
structures and to co...
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A commonly used guide in the XZ(occlusal) plane, in establishing a
treatment midpoint, is the median
palatal raphe.
 Its ...
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 In

some patients, the facial midline is
not a straight line but rather a curve;
hence, the facial midline could be
refe...
Mandibular midline
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It is more precise to mark the
anteriorpoint of the mandibular midline
using the mental spine fil...
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One more method is making lines
connecting the corners of the mouth
(chelion to chelion), the transverse
occlusal pl...
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Patient determination of midline

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Incisor-Apical Base Midpoints
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Found on apical bases of maxilla and
mandible.
It is necessary to construct the api...
Incisor-Apical Base Midpoints
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Used to evaluate skeletal asymmetry
In the sagittal view (Y-Z plane),
measuring the ...
 In

the frontal view (Y-Xplane),
measuring the apical base midpoints
relative to the transverse occlusal plane
allows on...
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Rationale for selecting
 Biological

:

Forces exerted by muscles, transseptal
fibers and orthodontic appliances tend to
...
MEASUREMENT
A perpendicular line from the upper and
lower apical base midpoints is extended to
the respective treatment oc...
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In some patients, orthognathic surgery is required to
achieve coincidence of the apical base midpoints.
For l...
The posterior midpoint
It is the geometric center of the arch
circumference.
 Starting from the desired position of the
f...
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Intramaxillary asymmetry

-Transverse symmetry
-Anteroposterior symmetry
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These symmetry analyses estimate the rig...
 The

tuberosity plane is the
reference plane for comparing
anteroposterior symmetry.
 This plane is perpendicular to th...
Maxillary midline

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 The

following findings are derived
from this type of intramaxillary
assessment of the study casts.
 Symmetric/asymmetr...
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Analysis of Anteroposterior
Symmetry
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Reveals the following:
Asymmetric mesiodistal tooth position of
correspondi...
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2. Vertical occlusal evaluation: The
presence of a canted occlusal plane
 The

cant in the occlusal plane can be
readily ...
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3. Transverse and anteroposterior occlusal evaluations
Asymmetry in the bucco-lingual
relationship e.g. a unilateral poste...
4.

Transverse skeletal and soft tissue
evaluation: In addition to the
bilateral structural comparisons,
deviations in the...
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The clinical examination should include an
intraoral examination with an evaluation of
the dental and facial midline...
•Facial and intraoral photographs are
indispensable.
A thorough facial examination must be conducted
to evaluate asymmetri...
 Examination

of each dental arch and
quadrant should be evaluated by using Oriented dental casts
 Occlusograms
 Symme...
 The

diagnosis of a rotary displacement
of the maxilla may require further
evaluation by mounting the dental
casts by fa...
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B: Radiographic examination

1.The lateral cephalogram:, provides
useful information in ramal height,
mandibular length an...
2.The panoramic radiograph: The
presence of gross pathology, missing
,supernumerary teeth can be
determined.
The shape of ...
3.Postero-anterior projection: It is a
valuable tool in the study of the right and left
structures since they are located ...
 Refined

diagnostic tools, such as
computerized tomographic images
and stereo photogrammetry, allow
three-dimensional an...
TREATMENT
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Dental asymmetries and a variety of
functional deviations can be treated
orthodontically.
Significant s...
Treatment Strategies
Breakspear advocates adapting the
occlusion by "stoning" (occlusal
equilibration).
 This method of t...
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Lewis advocates a sliding yoke and intermaxillary
elastics.
He states midline deviation exists mostly in C...
 Angle

used a Class III elastic with a
anterior diagonal elastic in
conjunction with arch expansion for
the correction o...
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 Proffit

admits that minor discrepancies
in midline coordination can be handled
in the finishing stages with
asymmetric ...
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If one side of the arch is corrected and
other side is not, then heavy unilateral
class II or class III elastics can be
us...
Parallel cross-elastics can also be given
when entire maxilla is displaced
transversely in relation to mandible.
 In fini...
 Elastics

along with coil springs can also
be used.
 Open coil springs on the side of
deviation

 Close

coil springs ...
 Alexander

advocates use of a heavy

anterior diagonal elastic supported by
a Class II or Class III elastic,
depending o...
 Begg

and Kesling state that the
proper balancing of space-closing classI
elastics coupled with appropriate Class
II tra...
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 Augmenting

a unilateral Class II
elastic, an anterior diagonal elastic, and
a Class III elastic with uprighting
springs...
 Begg

also advocated use of
asymmetric arch wire form for
correcting asymmetric arches
 He advocated use of round wire ...
Hazards of Asymmetric elastic
wear
 May

cause undesirable side effects if
skeletal balance already exists.
 The force v...
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If mandibular shift or rotation is not the
causative factor but rather the midline
deviation was a result of a denta...
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 Gianelly

and Paul advocated a
biomechanical system for midline
correction with second-order bends
used to move teeth on...
 Lewis

proposes the use of distal
spring mechanics as opposed to
second-order bends, bolstered by a
sliding yoke off Cla...
 Strang

and Thompson introduced a
double vertical spring loop assembly
to move the four incisors "en masse"
 A modifica...
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A 0.020-inch arch wire is divided into three
parts: two posterior and one anterior. The arch
wire thus is segment...
 The

closing loop is constructed as close
as possible to the canine, with the
section to be activated lying anterior to
...
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 In

cases in which the midline
discrepancy is very slight (1 to 2 mm),
it is tempting to tip the anterior teeth
into a p...


Discrepancies due to bodily rotation
as a result of crowding especially in mixed
dentition are corrected -by using fixe...
Other appliances
 Unilateral

molar distalization
appliances:
-power arm face bow
-spring attachment face bow
-soldered a...
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Power arm facebow:
In this design the side to receive more
distalizing force is longer and wider than the
ot...
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Asymmetric Extractions Used in the
Treatment of Patients With
Asymmetries
Creative approach for managing
dental asymmetrie...
A case presenting a number of dental arch asymmetries
including: retained mandibular left second deciduous
molar; congenit...
Post treatment intraoral, facial and model photographs
of the same patient. Treatment included extraction of
the deciduous...
Mandibular Dental Midline Deviation with
Skeletal Symmetry
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In 50% of all Class II malocclusions, majority
have di...
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If the molar on the Class II side is in an endon relationship, Class I closure mechanics
can be used in all three extra...
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Unilateral Class III malocclusion
One premolar extraction on the Class III
side would allow for primarily Class I
closure ...
Maxillary Dental Midline Deviation
With Skeletal Symmetry
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In the adult patient, non extraction correction
of the ...
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If extractions in the mandibular arch are
necessary because of excessive crowding,
and if a Bolton's tooth size discrep...
Maxillary and Mandibular Dental
Midline Deviation With Skeletal
Symmetry

A) Both deviated to one side
Extraction of ipsil...
b) If the maxillary and mandibular midlines
are both off from the facial midline, but in
this instance on opposite sides f...
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Jasper Jumper for mid line
correction
 Significant

midline discrepancies,
often due to anchorage loss, must
sometimes be...
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Flexible Jumper produces a range of
force from 1-16oz, depending on its
length when the teeth occlude.
Therefore use...
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Case exampleDiagnosis
A 10-year-old male showed a moderate facial asymmetry,.
A functional crossbite on the...
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Treatment Progress
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Treatment was initiated with a bonded Minne-Expander, using
a spring force of about 450g, to...
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Despite the asymmetrical orthodontic mechanics
and good dental alignment, the midline discrepancy
remained
It ...
 After

about four months of this
treatment, the intrusive effect of the
Class III jumper could be observed in the
maxill...
Asymmetrical intermaxillary elastics can correct midline discrepancy of more
than 3mm,but extrusive vertical force vectors...
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Clinical results seem to indicate condyle -fossa
remodeling as a normal adaptation to the
maxillary skeletal and ...
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Facilitation of Midline Correction
with a Premolar Extraction
Sequence
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CASE EXAMPLEDiagnosis
A 16-year-old male ...
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Camouflage comprehensive orthodontic treatment
was planned as follows:
1. Sequential extraction of the four first premolar...
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Treatment Progress
The maxillary left first premolar and
mandibular first premolars were extracted.
 The maxillary right ...
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Functional asymmetriestreatment
Mild deviations are corrected with minor
occlusal adjustments.
 Severe deviations need or...
Functional shifts can also be the result of
a skeletal asymmetry
 Rapid maxillary expansion,
orthognathic surgery and ort...
Treatment of asymmetrries
A) diverging occlusal planes


Canted anterior occlusal plane (in
transverse direction). The co...
B)Canted maxillary anterior
occlusal plane and a deep bite
 One

-piece intrusion arch of 0.017
´ 0.025-inch titanium mol...
0.017 x 0.025-inch TMA intrusion arch comes from molar
auxiliary tube and is tied to one side of anterior segment (0.018
x...
 If

the canine also requires intrusion,
this is performed in a separate stage
after the incisor intrusion.
 A simple ca...
A. Anterior view of separate canine intrusion. 0.018 x 0.025inch stainless steel arch wire bypasses canine. 0.017 x 0.025i...
 When

only one side requires
extrusion,
 A unilateral cantilever can be used
to correct the occlusal cant. The
cantilev...
Diagrammatic representation of unilateral extrusion of
canted anterior segment. 0.017 x 0.025-inch TMA cantilever
coming f...
C)Canted posterior occlusal
plane (in anteroposterior
direction)
A variation of the intrusion arch can be
used to correct ...
To upright buccal segment, cantilever with hook
can be used. Side effects are extrusion of buccal
segment and unilateral i...
D)Asymmetric arch formtreatment
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Orthodontists often use an asymmetrically shaped arch
wire or asymmetric interarc...
E)Treatment of asymmetric left
and/or right buccal occlusion
Clinical example A: for example, Class
I on one side and Clas...
Clinical example B: differences
in left and right molar rotation
Rotated molars are frequently seen in the
maxillary arch....
Clinical example C: no difference in
molar rotation and/or axial inclination
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The right and left molar relatio...
Treatment of skeletal
asymmetries- Surgical
 The

severity and nature of the skeletal
asymmetry will dictate whether the
...
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Asymmetries of a skeletal nature treated with
orthodontics alone might dictate certain
compromises
Severe discrep...
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The mandible is the dominant contributor to
dentofacial asymmetry in as much as it forms
the skeletal support for...
The clinician should consider several
guidelines
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Thoroughly evaluate the initial history and
diagnostic record...
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Treatment objectives should be to
coordinate arches
Minimize compensations such as axial
inclinations of the maxil...
Unilateral condylar hyperplasia
(hemimandibular hyperplasia,
hemimandibular elongation)

Because the surgical treatment st...
Unilateral condylectomy in a growing
child with condylar hyperplasia can
provide satisfactory resolution of facial
asymmet...
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A Le Fort I osteotomy to superiorly
reposition the affected side and bilateral
mandibular ramus osteotomies will
...
Genioplasty (augmentation or
redeuction) to further correct the chin
asymmetry
 Inferior border mandibular
osteotomy to c...
Orthodontic therapy is directed at ideally
positioning the teeth over basal bone.
 Segmented arch mechanics are often
ind...
Bony ankylosis of the TMJ
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
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Gap arthroplasty
Interpositional arthroplasty The
ankylosis should be surgically rele...
 Unilateral

internal derangenents
are corrected by articular disc
repositioning procedures,
stabilisation or replacement...
Hemifacial microsomia

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Severity of this condition can be extremely
varied and treatment should be initiated early
t...
Surgery for Hemifacial
Microsomia
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There are three stages of surgical intervention
described by Converse.
The in...
Initial Surgical Phase:
Augmentation of Deficiencies.
 Augmentation

of mandible can be
accomplished by an inverted L
ost...
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Second Surgical Phase: Jaw
Relationships.
Depending on growth, additional
mandibular advancement, usually
with vertical el...
Asymmetric inferior border
osteotomy to bring the chin to the
midline, which improves both lip function
and esthetics.
 A...
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When the bilateral osteotomies have been
completed, the mandible is repositioned and
bone grafts harvested from t...
Third Surgical Phase:
Contour Modification.
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If severe problems persist, major
reconstructive surgery with placeme...
Many asymmetric surgical orthodontic
cases are variations of other hypoplastic or
hyperplastic mandibular deformiities and...
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Genioplasty
Mandibuloplasty
Soft -tissue augmentation/ reduction,
and inferior-border
augmentation/reduction pro...
Condylar Fractures: Asymmetry
due to Trauma
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In most cases, the fractured condyle resorbs
and a new ramus articu...
 The

recommended management for a
child with a recent condylar fracture is
immobilization of the jaw for a few
days, unt...
 When

condylar segment is displaced
laterally or wedged between the ramus
and temporal bone, preventing motion
on the in...
Management of Posttraumatic Asymmetry
occurs because there is more growth on the
normal than on the affected side.
 If
po...
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Surgical intervention in the TM joint is
decided when previous therapy hasn’t
worked.
Release of the ankylosis...
REFERENCES
Shroff B, Siegel SM., Treatment of patients with asymmetries
using Semin Orthod. 1998 Sep;4(3):165-79. Review a...
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
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

Wong AM, Rabie AB ., Facilitation of midline correction
with a premolar extraction sequence.
J Clin Orth...
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Treatment of Mid line Discrepancies & skeletal assymmetries /certified fixed orthodontic courses by Indian dental academy

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Treatment of Mid line Discrepancies & skeletal assymmetries /certified fixed orthodontic courses by Indian dental academy

  1. 1. TREATMENT OF MIDLINE DISCREPANCIES AND SKELETAL ASYMMETRIES INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. INTRODUCTION Midline coordination and relative symmetry are basic to an appreciation of facial harmony and balance. Although a subtle asymmetry of the midlines is within normal limits, significant midline discrepancies can be quite detrimental to dentofacial esthetics. www.indiandentalacademy.com
  3. 3.    Stedman’s Medical Dictionary defines symmetry as “equality or correspondence in form of parts distributed around a center or an axis, at the two extremes or poles, or on the two opposite sides of the body.” Clinically, symmetry means balance while significant asymmetry means imbalance. Facial asymmetry, was probably first observed by the artists of early Greek staturary www.indiandentalacademy.com
  4. 4.    Mammals have marked asymmetry as to the placement of the viscera in the body cavity. Also functional as well as morphological asymmetries, e.g. right and left handedness, preference for one eye or one leg. Some asymmetries are embryonically rooted and are associated with asymmetry in the central nervous system. www.indiandentalacademy.com
  5. 5.  Each human being a unique individual.  Variations in the size, shape and relationship of the dental, skeletal and soft tissue facial structures are important in providing each individual with his or her own identity.  Perfect bilateral body symmetry is largely a theoretical concept that seldom exists in living organisms www.indiandentalacademy.com
  6. 6. Asymmetry in craniofacial areas can be recognized as differences in the size or relationship of the two sides of the face. This may be the result of discrepancies either in the form of individual bones, or a malposition of one or more bones in the craniofacial complex. The asymmetry may also be limited to the overlying soft tissues. www.indiandentalacademy.com
  7. 7.  Peck and Peck evaluated bilateral facial symmetry in 52 “exceptionally well-balanced” white adults and observed that there is less asymmetry and more dimensional stability as the cranium is approached.  In a study, Vig and Hewitt evaluated 63 posteroanterior cephalograms of “normal” children 9–18 years of age. Normal, in this case, meant that the child exhibited no clinically evident facial asymmetry  www.indiandentalacademy.com
  8. 8.     An overall asymmetry was found in most of the children with the left side being larger. The cranial base, and mandibular regions exhibited a left side excess while the maxillary region showed a larger right side. The dento-alveolar region exhibited the greatest degree of symmetry. Vig and Hewitt concluded that compensatory changes seem to operate in the development of the dentoalveolar structures and enable bilateral symmetrical function and maximum intercuspation to occur, thus minimizing the effects of the underlying asymmetry www.indiandentalacademy.com
  9. 9.  Results from a study by Miller et al indicate that the maxillary midline is situated in the exact middle of the mouth (using the philtrum as a guide) in approximately 70% of individuals, but that the maxillary and mandibular midlines coincide in only one fourth of the population. www.indiandentalacademy.com
  10. 10.  Midline correction should be undertaken from the initiation of treatment and once all midlines are coordinated they should be maintained as a guide for any further force systems used in completing the case  Differential diagnosis and appropriate inter and intraarch mechanotherapy is necessary. www.indiandentalacademy.com
  11. 11. Careful attention to midline coordination and attendant facial symmetry can aid the practitioner in achieving the following: 1. Maximum intercuspation and function 2. Stability in the finished result 3. The promotion of anterior dental and facial esthetics 4. A decrease in the potential for TMJ dysfunction 5. Maximizing self-satisfaction by achieving an increased number of ideal orthodontic results  www.indiandentalacademy.com
  12. 12. Etiology of midline discrepancies and Asymmetry  Includes a) Genetic or congenital malformations e.g. hemifacial microsomia and unilateral clefts of the lip and palate; multiple neurofibromatosis b) Environmental factors , e.g. habits and trauma; c) Functional deviations , e.g. mandibular shifts as a result of tooth interferences. www.indiandentalacademy.com
  13. 13. d. Epigenetic factors; and acquired factors, for example, infections or pathology Facial asymmetries can be classified based on the time of onset, as outlined by Picuiniemi.  Anomalies may originate during the prenatal period and be embryonic in nature or may have developed during the fetal term. www.indiandentalacademy.com
  14. 14.  Mandibulofacial asymmetries have a postnatal expression.  The causes are  Tumors in the TMJ region  Condylar hyperplasia or hypoplasia,  Hemifacial atrophy (Romberg syndrome),  Scleroderma www.indiandentalacademy.com
  15. 15.  Inflammatory arthritic disease  Ankylosis  Intra-articular disorders with an associated arthrosis  Condylar fracture  Damage to a nerve may indirectly lead to asymmetry from the loss of muscle function and tone. www.indiandentalacademy.com
  16. 16. Other factors  Intra-uterine pressure during pregnancy and significant pressure in the birth canal during parturition can have observable effects on the bones of the fetal skull. Molding of the parietal and facial bones from these pressures can result in facial asymmetry.  Osteochondroma of the mandibular condyle results in facial asymmetry, open bite on the involved side, and mandibular deviation www.indiandentalacademy.com
  17. 17. Localized factors           Early loss of a deciduous tooth Rotation of the entire dental arch and its supporting skeletal base. Asymmetric crowding in anterior section Prolonged retention of primary tooth Periodontal trauma and migration. Juvenile rheumatoidarthritis Dental caries Mandibular fractures Drifting and tipping of teeth. Congenitally missing teeth www.indiandentalacademy.com
  18. 18.  Lundstrom stated that asymmetry can be genetic or nongenetic in origin and is usually a combination of both.  Some right-left asymmetries in the oral cavity could be the result of environmental factors, eg,  sucking habits or asymmetric chewing habits caused by dental caries, extractions, and trauma. www.indiandentalacademy.com
  19. 19. Facial photographs of a patient with hemifacial microsomia. The discrepancies involve one side of the face only and include asymmetries in the mandibular body, ramus and condyle as well as the external and internal structures of the ear. Hemifacial microsomia www.indiandentalacademy.com
  20. 20. Asymmetry of Face due to fracture of TMJ www.indiandentalacademy.com
  21. 21. Intrauterine moulding resulting in midface deficiency www.indiandentalacademy.com
  22. 22. Deformation of second branchial arch with corresponding malformations www.indiandentalacademy.com
  23. 23. Facial asymmetry due to missing masseter muscle www.indiandentalacademy.com
  24. 24. Hemimandibular hypertrophy www.indiandentalacademy.com
  25. 25.     According to Lundstrom, asymmetry can also be described as qualitative (all or none) or quantitative. Examples of Quantitative asymmetries – differences in the number of teeth on each side The presence of a cleft lip and palate. Qualitative asymmetries could be differences in the size and shape of teeth, their location in the arches www.indiandentalacademy.com
  26. 26. Skeletal asymmetries-classification Obwegeser classification as described in the Journal of Maxillofacial Surgery in 1986.  Hemimandibular elongation  Hemimandibular hyperplasia. It is important to differentiate between the two types because: (1) The timing of growth cessation is different (2) The dentoalveolar compensations are different (3) The likelihood of successful interception is different.  www.indiandentalacademy.com
  27. 27. Hemimandibular elongation  Can occur as elongation either of the condyle or ramus in the vertical plane or the mandibular body in the horizontal plane.  Combinations are also possible. www.indiandentalacademy.com
  28. 28.     Features Mandible deviates to the opposite side of the deformity Exhibits flattening of the gonial angle on the affected side The mandibular borders and occlusal planes will superimpose on a centric relation cephalometric radiograph because there is no vertical component to the asymmetry www.indiandentalacademy.com
  29. 29. Mandibular elongation tends to stop when body or facial growth stops as it follows more of a somatic growth curve.  Presence of a unilateral posterior crossbite on the opposite side from the elongation.  Excessive growth occurs along normal growth axes.  www.indiandentalacademy.com
  30. 30. Hemimandibular hyperplasia  Recognized by entire half of the mandible being enlarged.  Features  Mandibular lower border midline “notching” on the panoramic film  Increased distances from the tooth apices to the lower border of the mandible when compared to the normal contralateral side. www.indiandentalacademy.com
  31. 31.  Hyperplasia, tends to grow longer exhibiting “latent” growth.  The midline usually deviates to the same side as the deformity.  Hyperplasia shows a normal or more acute gonial angle due to excessive vertical development.  Vertical differences in both planes can be observed in mandibular hyperplasia. www.indiandentalacademy.com
  32. 32.  Hemimandibular hyperplasia, however, is just about always overgrowth as in Angle Class III malocclusion that results from mandibular prognathism.  Most hemimandibular elongations are, in fact, Angle Class II or hypoplasias. This is why they are thought of as a variation of normal growth and not pathoses. www.indiandentalacademy.com
  33. 33. Structural classification of dentofacial asymmetries a. Dental asymmetries: These can be due to: local factors such as early loss of deciduous teeth , congenitally missing tooth, and habits such as thumb sucking. asymmetries in mesiodistal crown diameters.  Garn et al. found that tooth size asymmetry generally does not involve an entire side of the arch. www.indiandentalacademy.com
  34. 34. Teeth in the same morphological class tend to have the same direction of asymmetry.  Asymmetry tends to be greater for the more distal teeth in each morphological class i.e. the lateral incisors, second premolars and third molars.  Asymmetry may also be confined to the shape of the dental arches.  www.indiandentalacademy.com
  35. 35. b.Skeletal asymmetries: The deviation may involve one bone such as the maxilla or mandible , or it may involve a number of skeletal and muscular structures on one side of the face, e.g.hemifacial microsomia c. Muscular asymmetries- hemifacial atrophy or cerebral palsy.  Abnormal muscle function often results in skeletal and dental deviations www.indiandentalacademy.com
  36. 36. Patient with a skeletal mandibular asymmetry. The mandibular dental midline was shifted 7.0 mm to the left of the maxillary midline. The right side had a severe Class III relationship while the left side was closer to a Class I relationship www.indiandentalacademy.com
  37. 37. Post treatment photographs. Despite correction of the skeletal asymmetry some soft tissue facial asymmetry remained. Note that the mandibular midline was slightly over-corrected www.indiandentalacademy.com
  38. 38. d.  Functional asymmetries: These can result from the mandible being deflected laterally or antero-posteriorly, if occlusal interferences prevent proper intercuspation May be caused by a constricted maxillary arch or a malposed tooth, TMJ derangements and incoordination www.indiandentalacademy.com
  39. 39. Intraoral view of a patient in centric relation. Note the shift in the lower midline. Posterior occlusion was cusp on cusp buccolingually. www.indiandentalacademy.com
  40. 40. CLASSIFICATION -According to Steenbergen and Nanda  Dental asymmetries can be divided into four groups: 1. Diverging occlusal planes 2. Asymmetric left to right buccal occlusion, with or without midline deviation 3. Unilateral crossbite 4. Asymmetric arch form  www.indiandentalacademy.com
  41. 41. DIAGNOSIS  1. A: Clincial examination Evaluation of the dental midlines: includes an evaluation of the dental midlines in the following positions: mouth open; in centric relation; at initial contact; and in centric occlusion www.indiandentalacademy.com
  42. 42. Location of midline  Various points (landmarks) can be identified from the frontal head film, the frontal photographs, or by clinical examination  Additional landmarks, such as crista galli, the intermaxillary suture, and hard tissue pogonion,can be seen on the headfilm. These points happen to fall along the same line,. Unfortunately, this does not always happen. Because of a genuine asymmetry or by (1) an inability to visualize the structures, (2) head rotation in the cephalostat, (3) soft tissue flexibility, (4) an inexact technique .  www.indiandentalacademy.com
  43. 43. A symmetrical head can produce an asymmetrical posteroanterior film if the head is improperly oriented  Any rotation of the head distorts the constructed midpoints, with the greatest discrepancy noted at landmarks farthest from the film www.indiandentalacademy.com
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  45. 45.  Connecting the points-soft tissue nasion, subnasale and soft tissue pogonion- also locates midline  Can give variable results when repeated by the same orthodontist.  Some authors have proposed constructing additional landmarks by identifying bilateral structures and determining the midpoint between them. www.indiandentalacademy.com
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  49. 49.  Bisecting a line that connects corresponding bilateral landmarks may be invalid since absolute symmetry between right and left does not exist.  The closer bilateral structures are to the center of the face, the smaller the variation is in the midpoints as determined by a bisector www.indiandentalacademy.com
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  51. 51.  Another method for determining the facial midline is to establish a horizontal plane from skeletal structures and to construct a perpendicular line from a midpoint landmark  Two problems with this method. Difficulty of determining which landmark or constructed point to use, Any small variation in the horizontal plane can produce a large deviation in the facial midline.   www.indiandentalacademy.com
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  54. 54. A commonly used guide in the XZ(occlusal) plane, in establishing a treatment midpoint, is the median palatal raphe.  Its limitations include  Errors in the construction of a single line since curvature may be present  Correlation to other soft tissue facial structures is lacking.  www.indiandentalacademy.com
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  56. 56.  In some patients, the facial midline is not a straight line but rather a curve; hence, the facial midline could be referred to as the facial mid-arc.  Philtrum of upper lip can also be used to establish maxillary midline. www.indiandentalacademy.com
  57. 57. Mandibular midline   It is more precise to mark the anteriorpoint of the mandibular midline using the mental spine film or by using the lingualfrenum (Korkbaus1939). The posterior point for construction of the mandibular midline is determined by a perpendicular, which runs from the posterior edge of the midpalatal raphe from the maxillary to the mandibular cast. www.indiandentalacademy.com
  58. 58.   One more method is making lines connecting the corners of the mouth (chelion to chelion), the transverse occlusal plane, and the upper and lower lip horizontals Soft tissue midpoints (cupid's bow, center of the philtrum, and subnasale) are projected onto the horizontal planes and are visually compared to the incisor midpoints. (TOP = treatment occlusal plane.) www.indiandentalacademy.com
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  60. 60. Patient determination of midline www.indiandentalacademy.com
  61. 61. Incisor-Apical Base Midpoints    Found on apical bases of maxilla and mandible. It is necessary to construct the apical base midpoints by placing a point at approximately the midpoint of each of the incisor roots occlusogingivally and then finding their average mediolaterally These two midpoints, one in the maxilla and one in the mandible, are known as the upper and lower apical base midpoints www.indiandentalacademy.com
  62. 62. Incisor-Apical Base Midpoints    Used to evaluate skeletal asymmetry In the sagittal view (Y-Z plane), measuring the apical base points, A and B, relative to the occlusal plane, is helpful in determining the anteroposterior denture base discrepancy. The farther apart they are, the more difficult it is to correct the Class II or Class III malocclusion. www.indiandentalacademy.com
  63. 63.  In the frontal view (Y-Xplane), measuring the apical base midpoints relative to the transverse occlusal plane allows one to determine the transverse denture base discrepancy. www.indiandentalacademy.com
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  65. 65. Rationale for selecting  Biological : Forces exerted by muscles, transseptal fibers and orthodontic appliances tend to tip teeth about a point, generally near the root center as measured from the cementoenamel junction to the root apex.  Apical base midpoints serve as useful functional landmarks in planning the position of the treatment midpoint and midline  www.indiandentalacademy.com
  66. 66. MEASUREMENT A perpendicular line from the upper and lower apical base midpoints is extended to the respective treatment occlusal plane.  Ideally, the upper and lower perpendicular lines coincide at their intersection with the occlusal plane, a sign of no transverse apical base discrepancy  A transverse apical base discrepancy exists when the upper and lower apical base midpoints do not coincide  www.indiandentalacademy.com
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  68. 68.      In some patients, orthognathic surgery is required to achieve coincidence of the apical base midpoints. For less severe apical base midpoint discrepancies or for patients who wish to avoid surgery,the choice of treatment midpoints is – Asymmetric mechanics Minimal lateral translation Anchorage control www.indiandentalacademy.com
  69. 69. The posterior midpoint It is the geometric center of the arch circumference.  Starting from the desired position of the first molars (red line), equal radii are marked off on the right and left sides (blue lines). Where the right and !eft radii cross anteriorly, the posterior midpoint is located.  Determines the mesiodistal location of the posterior teeth.  www.indiandentalacademy.com
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  71. 71.  Intramaxillary asymmetry -Transverse symmetry -Anteroposterior symmetry   These symmetry analyses estimate the right-left differences in transverse and anteroposterior tooth positions (Korbitz1909). The midpalatal raphe defined by two anatomical points on the palatine raphe is the reference plane for the transverse symmetry analysis. www.indiandentalacademy.com
  72. 72.  The tuberosity plane is the reference plane for comparing anteroposterior symmetry.  This plane is perpendicular to the midpalatal raphe and runs through the distal-most tuberosity. www.indiandentalacademy.com
  73. 73. Maxillary midline www.indiandentalacademy.com
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  75. 75.  The following findings are derived from this type of intramaxillary assessment of the study casts.  Symmetric/asymmetric width development between right and left sides of the arch  Congruence/incongruence between dental midline and skeletal midline of the arches (dental midline shift) www.indiandentalacademy.com
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  79. 79. Analysis of Anteroposterior Symmetry     Reveals the following: Asymmetric mesiodistal tooth position of corresponding teeth in the right and left sides of the dental arches This analysis serves to diagnose any mesial tooth drift. This involves drawing a line parallel to the tuberosity plane, which runs through the posterior surface of the distal-most first molar, and comparing the sagittal distances of the individual posterior teeth www.indiandentalacademy.com
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  81. 81. 2. Vertical occlusal evaluation: The presence of a canted occlusal plane  The cant in the occlusal plane can be readily observed by asking the patient to bite on a tongue blade to determine how it relates to the inter-pupillary plane. www.indiandentalacademy.com
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  83. 83. 3. Transverse and anteroposterior occlusal evaluations Asymmetry in the bucco-lingual relationship e.g. a unilateral posterior crossbite www.indiandentalacademy.com
  84. 84. 4. Transverse skeletal and soft tissue evaluation: In addition to the bilateral structural comparisons, deviations in the dorsum and tip of the nose as well as the philtrum and chin point need to be determined www.indiandentalacademy.com
  85. 85.   The clinical examination should include an intraoral examination with an evaluation of the dental and facial midlines and detection of TMJ derangements. Operator-assisted natural head position, mandibular centric relation, and soft tissue in repose are used to accurately assess the frontal and profile views. www.indiandentalacademy.com
  86. 86. •Facial and intraoral photographs are indispensable. A thorough facial examination must be conducted to evaluate asymmetries in facial morphology www.indiandentalacademy.com
  87. 87.  Examination of each dental arch and quadrant should be evaluated by using Oriented dental casts  Occlusograms  Symmetroscopes www.indiandentalacademy.com
  88. 88.  The diagnosis of a rotary displacement of the maxilla may require further evaluation by mounting the dental casts by face-bow transfer on to semiadjustable articulator  Finally, mounted dental casts and model surgery are essential in planning treatment for patients requiring surgical orthodontic www.indiandentalacademy.com
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  90. 90. B: Radiographic examination 1.The lateral cephalogram:, provides useful information in ramal height, mandibular length and gonial angle. It is limited by the fact that the right and left structures are superimposed on each other and are at different distances from the film and x-ray source resulting in significant differences in magnifications. www.indiandentalacademy.com
  91. 91. 2.The panoramic radiograph: The presence of gross pathology, missing ,supernumerary teeth can be determined. The shape of the mandibular ramus and condyles on both sides can be grossly compared  Geometric distortions are significant www.indiandentalacademy.com
  92. 92. 3.Postero-anterior projection: It is a valuable tool in the study of the right and left structures since they are located at relatively equal distances from the film and x-ray source  Comparison between sides is therefore more accurate  PA cephalograms can be obtained in centric occlusion as well as with the mouth open.  The latter position might help determine the extent of the functional deviation www.indiandentalacademy.com
  93. 93.  Refined diagnostic tools, such as computerized tomographic images and stereo photogrammetry, allow three-dimensional analyses of the craniofacial complex. These methods can generate, with the aid of a computer, a three-dimensional image of the patient's face. With a coordinate system, the asymmetries can be quantified. www.indiandentalacademy.com
  94. 94. TREATMENT    Dental asymmetries and a variety of functional deviations can be treated orthodontically. Significant structural facial asymmetries are not easily amenable to orthodontic treatment. These problems may require orthopedic correction during the growth period and/or surgical management at a later point. Patient complaints and desires need to be addressed since they may vary from unrealistic expectations to a lack of concern even in the presence of large deviations. www.indiandentalacademy.com
  95. 95. Treatment Strategies Breakspear advocates adapting the occlusion by "stoning" (occlusal equilibration).  This method of treatment allows the occlusion to function more properly but may not correct the dental or facial asymmetry.  www.indiandentalacademy.com
  96. 96.        Lewis advocates a sliding yoke and intermaxillary elastics. He states midline deviation exists mostly in Class II cases. The more frequent causes are Mandibular shift resulting from a posterior crossbite Tipping or drifting of the teeth Lateral mandibular rotation resulting from occlusal interferences, arch asymmetries, tooth size discrepancies Overretraction of the canines on one side www.indiandentalacademy.com
  97. 97.  Angle used a Class III elastic with a anterior diagonal elastic in conjunction with arch expansion for the correction of midline discrepancies www.indiandentalacademy.com
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  99. 99.  Proffit admits that minor discrepancies in midline coordination can be handled in the finishing stages with asymmetric Class II and Class III elastics  Or by using unilateral Class II or Class III intermaxillary elastics in tandem with an anterior diagonal elastic ,after extraction spaces have been closed. www.indiandentalacademy.com
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  101. 101. If one side of the arch is corrected and other side is not, then heavy unilateral class II or class III elastics can be used on the affected side.  If there is abnormal transverse relationship (cross bite) posteriorly leading to mandibular shift ,POSTERIOR CROSS -ELASTICS can be given  www.indiandentalacademy.com
  102. 102. Parallel cross-elastics can also be given when entire maxilla is displaced transversely in relation to mandible.  In finishing stages rectangular wire must be changed to round wire(.016 or .018) if asymmetric or unilateral elastics are used to facilitate midline correction.  www.indiandentalacademy.com
  103. 103.  Elastics along with coil springs can also be used.  Open coil springs on the side of deviation  Close coil springs on the side opposite of deviation  Activation should be controlled. www.indiandentalacademy.com
  104. 104.  Alexander advocates use of a heavy anterior diagonal elastic supported by a Class II or Class III elastic, depending on whether the original malocclusion was a Class II or Class III during the finishing stages,  In an extraction case it may be performed during space closure ,anterior diagonal elastic is then attached to the closing loops www.indiandentalacademy.com
  105. 105.  Begg and Kesling state that the proper balancing of space-closing classI elastics coupled with appropriate Class II traction during stage II keeps the midlines coordinated www.indiandentalacademy.com
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  107. 107.  Augmenting a unilateral Class II elastic, an anterior diagonal elastic, and a Class III elastic with uprighting springs to "walk the teeth" can effect midline changes www.indiandentalacademy.com
  108. 108.  Begg also advocated use of asymmetric arch wire form for correcting asymmetric arches  He advocated use of round wire as it leads to efficient tipping facilitating midline correction. www.indiandentalacademy.com
  109. 109. Hazards of Asymmetric elastic wear  May cause undesirable side effects if skeletal balance already exists.  The force vectors created by the elastics impart a moment to the mandible, ie, a tendency for rotation that may lead to a transient alteration in mandibular position. www.indiandentalacademy.com
  110. 110.   If mandibular shift or rotation is not the causative factor but rather the midline deviation was a result of a dental shifting or drifting of teeth, with the face being symmetric, then use of such mechanics would effect a change in mandibular position , potential for TMJ dysfunction. Canting of occlusal plane can occur as a result of vertical force vector of elastics. www.indiandentalacademy.com
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  112. 112.  Gianelly and Paul advocated a biomechanical system for midline correction with second-order bends used to move teeth on one side distally and create a space for shifting the midline. www.indiandentalacademy.com
  113. 113.  Lewis proposes the use of distal spring mechanics as opposed to second-order bends, bolstered by a sliding yoke off Class II traction to distalize upper posterior teeth in cases exhibiting arch asymmetry www.indiandentalacademy.com
  114. 114.  Strang and Thompson introduced a double vertical spring loop assembly to move the four incisors "en masse"  A modification of this arch wire (rectangular) configuration using round wire has come www.indiandentalacademy.com
  115. 115.    A 0.020-inch arch wire is divided into three parts: two posterior and one anterior. The arch wire thus is segmented. The two vertical loops allow for stabilization of the posterior segments as long as molar stops are used; hence only anterior movement takes place. The incorporation of a helix in each loop provides greater flexibility and longer activation. To activate, a ligature is passed through the circle on the closing loop side and tied to the contralateral lateral incisor bracket. Each tooth has been individually ligated to the anterior section of the arch, each posterior section having been ligated together as a unit. www.indiandentalacademy.com
  116. 116.  The closing loop is constructed as close as possible to the canine, with the section to be activated lying anterior to the helix.  When the closing loop is activated, the opening loop is condensed and a pushpull reaction occurs whereby all four anterior teeth shift "en masse" toward the desired side www.indiandentalacademy.com
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  119. 119.  In cases in which the midline discrepancy is very slight (1 to 2 mm), it is tempting to tip the anterior teeth into a position that coordinates with the facial midline with the help of removable appliances such as finger spring. www.indiandentalacademy.com
  120. 120.  Discrepancies due to bodily rotation as a result of crowding especially in mixed dentition are corrected -by using fixed appliance in the anterior section -relieving the crowding -teeth are then pushed to attain a proper midline, by using coil springs on side of deviation www.indiandentalacademy.com
  121. 121. Other appliances  Unilateral molar distalization appliances: -power arm face bow -spring attachment face bow -soldered arm face bow  Asymetric head gear  Pendulum appliance www.indiandentalacademy.com
  122. 122.       Power arm facebow: In this design the side to receive more distalizing force is longer and wider than the other Soldered offset facebow: Here the outer bow is attached to the side favored to receive the distalizing force Spring attachment face bow bilateral face bow but with a open coil spring placed distal to the stop on the side to be distalized www.indiandentalacademy.com
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  124. 124. Asymmetric Extractions Used in the Treatment of Patients With Asymmetries Creative approach for managing dental asymmetries is to extract a combination of teeth that will simplify intra-arch and interarch mechanics.  This reduces the dependency on patient compliance for elastic wear and may even shorten treatment time.  www.indiandentalacademy.com
  125. 125. A case presenting a number of dental arch asymmetries including: retained mandibular left second deciduous molar; congenitally missing mandibular left second premolar; and unilateral anterior crossbite between the maxillary lateral incisor and mandibular canine. www.indiandentalacademy.com
  126. 126. Post treatment intraoral, facial and model photographs of the same patient. Treatment included extraction of the deciduous tooth and three premolars www.indiandentalacademy.com
  127. 127. Mandibular Dental Midline Deviation with Skeletal Symmetry    In 50% of all Class II malocclusions, majority have distally positioned mandibular molars on the Class II side with mandibular canine on that side also positioned distally. If such a patient presented with the maxillary dental midline coincident with the facial midline,, a three- premolar extraction plan may be done The extraction of a mandibular premolar on the Class I side relocates the canine in a more distal position to match the contralateral canine. The extraction of two upper premolars would maintain the maxillary midline symmetry to the facial midline. www.indiandentalacademy.com
  128. 128.  If the molar on the Class II side is in an endon relationship, Class I closure mechanics can be used in all three extraction buccal segments.  Differential extraction pattern on the Class II side, such as the removal of a maxillary first premolar and mandibular second premolar to help lose lower molar anchorage can also be used The extraction of a mandibular premolar on the Class II side may minimize the flaring of incisors from Class II elastics by providing arch space for the mandibular molar to advance  www.indiandentalacademy.com
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  131. 131. Unilateral Class III malocclusion One premolar extraction on the Class III side would allow for primarily Class I closure mechanics  If the molar is in a full-step Class III relationship, a lingual arch that is either passive or unilaterally activated can be used to maximize molar anchorage on that side.  www.indiandentalacademy.com
  132. 132. Maxillary Dental Midline Deviation With Skeletal Symmetry    In the adult patient, non extraction correction of the Class II buccal segment is less predictable. Removal of a maxillary premolar on the Class II side would facilitate correction of the canine to a Class I relationship with no extraction in lower arch. A passive or tightly activated transpalatal arch could be used to control molar anchorage, and space closure could be accomplished primarily through Class I mechanics www.indiandentalacademy.com
  133. 133.  If extractions in the mandibular arch are necessary because of excessive crowding, and if a Bolton's tooth size discrepancy exists, the extraction of a lower incisor or lower incisor proximal reduction may simplify the biomechanical complexity of the case www.indiandentalacademy.com
  134. 134. Maxillary and Mandibular Dental Midline Deviation With Skeletal Symmetry A) Both deviated to one side Extraction of ipsilateral upper and lower premolars may be the plan to follow.  The decision to extract first or second premolars or a combination of these is dependent upon the amount of midline correction that is desired, and molar anchorage requirement  www.indiandentalacademy.com
  135. 135. b) If the maxillary and mandibular midlines are both off from the facial midline, but in this instance on opposite sides from each other, it is likely the result of asymmetric arch crowding.  The appropriate plan in this situation may be the extraction of an upper premolar on the Class II side and a mandibular premolar on the Class III side. www.indiandentalacademy.com
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  138. 138. Jasper Jumper for mid line correction  Significant midline discrepancies, often due to anchorage loss, must sometimes be corrected during the last phase of orthodontic treatment.  The Jasper Jumper, a flexible sagittal force module, was designed for the correction of Class II high angle malocclusions. www.indiandentalacademy.com
  139. 139.   Flexible Jumper produces a range of force from 1-16oz, depending on its length when the teeth occlude. Therefore used asymmetrically--one side with conventional Class II mechanics, the other with Class III mechanics--to correct a midline discrepancy and a possible mandibular shift resulting from maxillary deficiency. www.indiandentalacademy.com
  140. 140.       Case exampleDiagnosis A 10-year-old male showed a moderate facial asymmetry,. A functional crossbite on the right side, resulting from a narrow maxilla and the mandibular deviation to the right in habitual occlusion. The patient had a full-cusp Class II molar and cuspid relationship on the right side, but a Class I relationship on the left. collapsed maxillary arch, upper and lower anterior crowding, and a palatally positioned maxillary right lateral incisor. www.indiandentalacademy.com
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  142. 142. Treatment Progress     Treatment was initiated with a bonded Minne-Expander, using a spring force of about 450g, to correct the transverse discrepancy A unilateral medium-pull headgear was fitted later to the molar tubes embedded in the buccal acrylic of the expander to improve the skeletal relationship and to help correct the maxillary asymmetry. Leveling of the maxillary incisors and cuspids was initiated with Straight-Edge brackets After five months of unilateral headgear wear, similar mechanics were continued with a transpalatal bar ,also activated unilaterally www.indiandentalacademy.com
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  144. 144.     Despite the asymmetrical orthodontic mechanics and good dental alignment, the midline discrepancy remained It was decided to use asymmetrical Jasper Jumpers to obtain a more continuous and intensive force system on the maxillary complex. During the asymmetrical jumper application, the stiffest possible rectangular stainless steel archwires --.017" X .025" maxillary and .018" X . 025" mandibular--were placed The transpalatal bar was kept in place to counteract any side effects of the asymmetrical mechanics on the maxillary arch. www.indiandentalacademy.com
  145. 145.  After about four months of this treatment, the intrusive effect of the Class III jumper could be observed in the maxillary left anterior region, so a 4.5oz diagonal elastic (Zebra) was added from the maxillary left lateral incisor to the mandibular right lateral incisor.  By the end of sixth month, the midline was overcorrected and the posterior occlusion was satisfactory. www.indiandentalacademy.com
  146. 146. Asymmetrical intermaxillary elastics can correct midline discrepancy of more than 3mm,but extrusive vertical force vectors of Class III (F_1) and diagonal (F_2) elastics will theoretically exceed force vector of Class II side (F_3). Maxillary occlusal plane (MOP) may therefore be lower on left side, causing difficulties with fixed appliance mechanics. B. With asymmetrical Jasper Jumpers, vertical force vectors of Class III jumper (F_1) and diagonal elastic (F_2) are opposite. Even if forces are unequal, adverse effects will be less likely. www.indiandentalacademy.com
  147. 147.    Clinical results seem to indicate condyle -fossa remodeling as a normal adaptation to the maxillary skeletal and overall occlusal changes. The dental effects of this force system are reciprocal--the incisors moved bodily in opposite directions, while the direction and amount of movement were controlled by the sizes of the jumpers. The asymmetrical jumpers were well accepted by the patients, and no breakage occurred. www.indiandentalacademy.com
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  150. 150. Facilitation of Midline Correction with a Premolar Extraction Sequence     CASE EXAMPLEDiagnosis A 16-year-old male presented with the chief complaint of buccally erupting canines .The upper and lower midlines were shifted to the right by 4mm and 2mm, respectively. The patient had a convex profile, an obtuse nasolabial angle, a retrognathic mandible, and excessive upper and lower facial heights. The molar relationship was Class II on the right and Class I on the left; the overjet was 7mm. www.indiandentalacademy.com
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  152. 152. Camouflage comprehensive orthodontic treatment was planned as follows: 1. Sequential extraction of the four first premolars, with the maxillary left first premolar removed before the contralateral first premolar to allow correction of the upper midline and to conserve anchorage. 2. Maximum anchorage from a mandibular lingual holding arch and high-pull headgear. 3. Extraction of maxillary second molars as needed. www.indiandentalacademy.com
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  154. 154. Treatment Progress The maxillary left first premolar and mandibular first premolars were extracted.  The maxillary right first premolar was left in place to prevent distal drift of the right canine.  Preadjusted .018" brackets were bonded and an .016" nickel titanium archwire was placed.  www.indiandentalacademy.com
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  156. 156. Functional asymmetriestreatment Mild deviations are corrected with minor occlusal adjustments.  Severe deviations need orthodontic treatment to align the teeth and to obtain proper function.  Occlusal splints may be necessary to properly evaluate the presence and extent of the functional shift by eliminating habitual posturing and deprogramming the musculature.  www.indiandentalacademy.com
  157. 157. Functional shifts can also be the result of a skeletal asymmetry  Rapid maxillary expansion, orthognathic surgery and orthodontic treatment may be indicated in the management of these cases  www.indiandentalacademy.com
  158. 158. Treatment of asymmetrries A) diverging occlusal planes  Canted anterior occlusal plane (in transverse direction). The conventional treatment for this problem is the use of vertical interarch elastics to extrude the side of the occlusal plane that is farthest from the treatment occlusal plane. The vertical elastic exerts an extrusive force on both the maxillary and mandibular arches. www.indiandentalacademy.com
  159. 159. B)Canted maxillary anterior occlusal plane and a deep bite  One -piece intrusion arch of 0.017 ´ 0.025-inch titanium molybolenum alloy (TMA) is tied to that side of the anterior segment requiring intrusion.  The intrusive force level should be approximately 60 gm for four maxillary incisors and approximately 50 gm or less for four mandibular incisors. www.indiandentalacademy.com
  160. 160. 0.017 x 0.025-inch TMA intrusion arch comes from molar auxiliary tube and is tied to one side of anterior segment (0.018 x 0.025-inch stainless steel) delivering intrusive force on that side. B, Activated intrusion arch, before ligation on anterior segment. C, Intrusion arch tied in on one side only. www.indiandentalacademy.com
  161. 161.  If the canine also requires intrusion, this is performed in a separate stage after the incisor intrusion.  A simple cantilever (0.017 ´ 0.025inch TMA) exerting a force of 20 to 25 gm can be used www.indiandentalacademy.com
  162. 162. A. Anterior view of separate canine intrusion. 0.018 x 0.025inch stainless steel arch wire bypasses canine. 0.017 x 0.025inch TMA cantilever comes from molar auxiliary tube and is tied underneath canine bracket (point force contact) delivering intrusive force. B, Buccal view of separate canine intrusion. Ideally wire should not be tied into bracket slot to deliver force without moments. C, Buccal view of separate canine intrusion. www.indiandentalacademy.com
  163. 163.  When only one side requires extrusion,  A unilateral cantilever can be used to correct the occlusal cant. The cantilever, 0.017 ´ 0.025-inch TMA, comes out of the auxiliary tube of the first molar on the side where the extrusion is to take place and is hooked around the anterior segment. A force of approximately 30 gm is sufficient www.indiandentalacademy.com
  164. 164. Diagrammatic representation of unilateral extrusion of canted anterior segment. 0.017 x 0.025-inch TMA cantilever coming from auxiliary tube of molar is tied to one side of anterior segment. B, Patient with canted maxillary occlusal plane. C, Correction of canted occlusal plane with cantilever hook tied on affected side. www.indiandentalacademy.com
  165. 165. C)Canted posterior occlusal plane (in anteroposterior direction) A variation of the intrusion arch can be used to correct this along with a deep overbite.  The magnitude of force is increased to 150 gm that causes a large tip-back moment on the buccal segment, thereby, flattening the occlusal plane. This appliance delivers appropriate force to the area of the arch in need of correction.  www.indiandentalacademy.com
  166. 166. To upright buccal segment, cantilever with hook can be used. Side effects are extrusion of buccal segment and unilateral intrusion of anterior segment. www.indiandentalacademy.com
  167. 167. D)Asymmetric arch formtreatment    Orthodontists often use an asymmetrically shaped arch wire or asymmetric interarch elastics to correct an asymmetric arch form. A more efficient way is to use a cantilever (0.017 ´ 0.025-inch TMA) from the first molar, with a hook that is attached in the area where the arch needs to be expanded or narrowed. The cantilever can be inserted on top of a light arch wire, for example 0.016-inch TMA. A transpalatal or lingual arch connecting the molars should be in place to prevent rotation of the molar to which the cantilever is attached. www.indiandentalacademy.com
  168. 168. E)Treatment of asymmetric left and/or right buccal occlusion Clinical example A: for example, Class I on one side and Class II on the other. This can be due to differences in axial inclination of the molars  A lingual or palatal arch (0.032-inch TMA or 0.032 x 0.032-inch TMA) activation is made to deliver a tip forward moment on the Class I side and a tip-back moment on the Class II side  www.indiandentalacademy.com
  169. 169. Clinical example B: differences in left and right molar rotation Rotated molars are frequently seen in the maxillary arch. A mesial-in rotation of one molar often results in an asymmetric molar occlusion.  To correct this problem, a transpalatal arch is used with equal amounts of antirotation activation. An 0.018 x 0.025-inch stainless steel wire is tied into all teeth except the rotated molar  www.indiandentalacademy.com
  170. 170. Clinical example C: no difference in molar rotation and/or axial inclination      The right and left molar relationship can be asymmetric without perverted axial inclinations or rotations. A conventional approach to correct this problem is to use an asymmetric headgear. This headgear has the potential to move one molar further distally than the other molar Unilateral dental crossbite The treatment can be performed with a lingual arch (0.032-inch TMA) in the mandible and transpalatal arch (TPA) in the maxilla www.indiandentalacademy.com
  171. 171. Treatment of skeletal asymmetries- Surgical  The severity and nature of the skeletal asymmetry will dictate whether the discrepancy can be completely or partially resolved solely through orthodontic treatment.  In growing individuals, orthopedic appliances in conjunction with orthodontic treatment are used to help improve or correct the developing skeletal imbalances. www.indiandentalacademy.com
  172. 172.    Asymmetries of a skeletal nature treated with orthodontics alone might dictate certain compromises Severe discrepancies may require a combination of surgery and orthodontic treatment. Abnormalities of the coronoid and condylar processes as well as in the position and shape of the articular discs should be considered whenever limited opening, acute malocclusions, or mandibular deviations are found. www.indiandentalacademy.com
  173. 173.    The mandible is the dominant contributor to dentofacial asymmetry in as much as it forms the skeletal support for the soft tissues of the lower face. Conversely, the maxilla provides minimal soft-tissue support and has small part in asymmetry. Most maxillary asymmetry is secondary to asymetric mandibular growth and measured simply by the location of the maxillary dental midline and the cant of the frontal occlusal plane. www.indiandentalacademy.com
  174. 174. The clinician should consider several guidelines      Thoroughly evaluate the initial history and diagnostic records. Always check for a functional component to the malocclusion and take the appropriate records in centric relation. Recognize the early signs of a progressive asymmetry. Understand the dentoalveolar compensations associated. Take progress records and reevaluate if there is progressive asymmetry. www.indiandentalacademy.com
  175. 175.    Treatment objectives should be to coordinate arches Minimize compensations such as axial inclinations of the maxillary and mandibular dentition and transverse occlusal plane canting keeping the maxillary transverse occlusal plane as level as possible during growth by using splints and other types of passive appliances to prevent compensatory supraeruption. www.indiandentalacademy.com
  176. 176. Unilateral condylar hyperplasia (hemimandibular hyperplasia, hemimandibular elongation) Because the surgical treatment strategy depends on condylar growth activity, skeletal scintigraphy growth analysis or  A technetium-99m methylene diphosphonate (Tc99m) bone scan can also be performed.  www.indiandentalacademy.com
  177. 177. Unilateral condylectomy in a growing child with condylar hyperplasia can provide satisfactory resolution of facial asymmetry  Secondary deformities, such as canting of the maxillary frontal occlusal plane and chin deformities should also be corrected.  www.indiandentalacademy.com
  178. 178.    A Le Fort I osteotomy to superiorly reposition the affected side and bilateral mandibular ramus osteotomies will correct the cant of the frontal occlusal plane. Osteotomies can be simultaneously used to correct any accompanying anteroposterior, vertical, or transverse discrepancies. Condylar shave procedure can be done to correct minor deformities. www.indiandentalacademy.com
  179. 179. Genioplasty (augmentation or redeuction) to further correct the chin asymmetry  Inferior border mandibular osteotomy to correct the bowing on the affected side and/or augmentation of the inferior border on the contralateral side, may also be indicated  www.indiandentalacademy.com
  180. 180. Orthodontic therapy is directed at ideally positioning the teeth over basal bone.  Segmented arch mechanics are often indicated, particularly when the surgical plan calls for segmental osteotomies, but also when precision in leveling by intrusion, maximum anchorage retraction, segmental torque and tip, and/or control of the transverse dimension is required.  www.indiandentalacademy.com
  181. 181. Bony ankylosis of the TMJ     Gap arthroplasty Interpositional arthroplasty The ankylosis should be surgically released, biocompatible interpositional material should be placed eg. sialistic implants or bone grafts High condylar shave with disc stabilisation Condylectomy Distraction osteogenesis etc are some procedures to relieve ankylosis www.indiandentalacademy.com
  182. 182.  Unilateral internal derangenents are corrected by articular disc repositioning procedures, stabilisation or replacement followed by pharmacotherapy , occlusotherapy , physiotherapy, ultrasound etc  Rapid maxillary expansion can be used to correct transverse asymmetries www.indiandentalacademy.com
  183. 183. Hemifacial microsomia   Severity of this condition can be extremely varied and treatment should be initiated early to help prevent greater expression of the asymmetry. Distraction osteogenesis is an excellent treatment modality in the growing patient in an attempt to stimulate development of soft tissue as well as hard tissue. In more severe cases, reconstruction of the TMJ with costochondral grafting will usually be required www.indiandentalacademy.com
  184. 184. Surgery for Hemifacial Microsomia     There are three stages of surgical intervention described by Converse. The initial surgery is at age 5 to 8 years. The goal is to replace missing skeletal elements and augment severely deficient areas to create a more favourable environment for subsequent growth of unaffected areas. At age 12 to 15, after the adolescent growth spurt, orthognathic concerns are addressed, with repositioning of both jaws as necessary. The third stage, in the late teens, is designed to enhance the contour of the skeleton and the soft tissues. www.indiandentalacademy.com
  185. 185. Initial Surgical Phase: Augmentation of Deficiencies.  Augmentation of mandible can be accomplished by an inverted L osteotomy via an extra oral approach, with the placement of grafts as appropriate.  If the zygomatic arch is missing or severely deficient,one may be constructed at the initial stage. www.indiandentalacademy.com
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  189. 189. Second Surgical Phase: Jaw Relationships. Depending on growth, additional mandibular advancement, usually with vertical elongation of the affected ramus and the placement of a graft on that side, if necessary.  If sagittal correction is necessary, sagittal split osteotomies may be employed bilaterally.  www.indiandentalacademy.com
  190. 190. Asymmetric inferior border osteotomy to bring the chin to the midline, which improves both lip function and esthetics.  Additional onlay bone grafting to the mandible or maxilla for contour purposes also is performed   If occlusal cant persists beyond age 15, a LeFort I osteotomy to correct it may be required. www.indiandentalacademy.com
  191. 191.    When the bilateral osteotomies have been completed, the mandible is repositioned and bone grafts harvested from the cranium or the ilium are inserted into the vertical and horizontal defects and secured with wires, bone plates, or screws. Maxillomandibular fixation including an occlusal wafer splint is applied and continued for 4 weeks while healing takes place. Overcontouring the affected side with bone grafts helps camouflage some of the missing soft tissues. www.indiandentalacademy.com
  192. 192. Third Surgical Phase: Contour Modification.    If severe problems persist, major reconstructive surgery with placement of grafts in the zygomatic and/or mandibular ramus areas may be required Orthognathic surgery to reposition the jaws may be needed Occasionally, mandibular inferior border osteotomy or onlay bone grafts to augment deficient areas are planned to enhance the final result. www.indiandentalacademy.com
  193. 193. Many asymmetric surgical orthodontic cases are variations of other hypoplastic or hyperplastic mandibular deformiities and accordingly can be addressed byasymmetric movement of the mandibular distal segment using bilateral ramal osteotomies.  Sagittal split ramus osteotomy and the intraoral vertical ramus osteotomy are also commonly indicated in these cases  www.indiandentalacademy.com
  194. 194.     Genioplasty Mandibuloplasty Soft -tissue augmentation/ reduction, and inferior-border augmentation/reduction provide additional flexibility in correcting asymmetries. Not infrequently, maxilllary form and position must be corrected, necessitating simultaneous maxillary and mandibular osteotomies. www.indiandentalacademy.com
  195. 195. Condylar Fractures: Asymmetry due to Trauma     In most cases, the fractured condyle resorbs and a new ramus articulation forms. When growth restriction occurs, the ramus grows more on the normal side, the chin deviates toward the affected side. Less tooth eruption takes place there Restricted movements of mandible occur, termed as functional ankylosis because jaw movement and function occur but are impaired. www.indiandentalacademy.com
  196. 196.  The recommended management for a child with a recent condylar fracture is immobilization of the jaw for a few days, until initial soft-tissue healing can occur  Followed by physiotherapy to maximize jaw movement  Functional appliance to guide mandible to the proper position is indicated. www.indiandentalacademy.com
  197. 197.  When condylar segment is displaced laterally or wedged between the ramus and temporal bone, preventing motion on the injured side.  Closed manipulation to free the segment should be attempted first.  If mandibular motion is still restricted, an open approach is done , removing the condylar head or repositioning it. www.indiandentalacademy.com
  198. 198. Management of Posttraumatic Asymmetry occurs because there is more growth on the normal than on the affected side.  If possible bring the mandible to a normal symmetric position in the midline without undue strain, so that the construction bite for a functional appliance can be taken, treatment of this type should be attempted before any surgery  Or ramus osteotomy to bring the mandible to its approximately normal position www.indiandentalacademy.com
  199. 199.     Surgical intervention in the TM joint is decided when previous therapy hasn’t worked. Release of the ankylosis to provide free movement involves removing soft tissue and bone and excessive scar tissue The coronoid process must also be released or removed Physical therapy follows surgery to maintain the degree of jaw motion attained www.indiandentalacademy.com
  200. 200. REFERENCES Shroff B, Siegel SM., Treatment of patients with asymmetries using Semin Orthod. 1998 Sep;4(3):165-79. Review asymmetric mechanics Nanda R, Margolis MJ., Treatment strategies for midline discrepancies. Semin Orthod. 1996 Jun;2(2):84-9. . : Jerrold L, Lowenstein LJ. The midline: diagnosis and treatment. Am J Orthod Dentofacial Orthop. 1990 Jun;97(6):453-62. : Rebellato J., Asymmetric extractions used in the treatment of patients with asymmetries. Semin Orthod. 1998 Sep;4(3):180-8. : van Steenbergen E, Nanda R, Biomechanics of orthodontic correction of dental asymmetries. Am J Orthod Dentofacial Orthop. 1995 Jun;107(6):618-24. Burstone CJ., Diagnosis and treatment planning of patients with asymmetries. Semin Orthod. 1998 Sep;4(3):153-64. : Erdogan E, Erdogan E., Asymmetric application of the Jasper Jumper in the correction of midline discrepancies. J Clin Orthod. 1998 Mar;32(3):170-80.. www.indiandentalacademy.com
  201. 201.        Wong AM, Rabie AB ., Facilitation of midline correction with a premolar extraction sequence. J Clin Orthod. 2001 Jan;35(1):13-7 Joondeph DR. Mysteries of asymmetries.Am J Orthod Dentofacial Orthop. 2000 May;117(5):577-9. Bishara SE, Burkey PS, Kharouf JG ., Dental and facial asymmetries: a review. Angle Orthod. 1994;64(2):8998. Contemporary orthodontics-proffit Surgical orthodontics-proffit and white Kusnoto J, Evans CA, BeGole EA, Obrez A . Orthodontic correction of transverse arch asymmetries. Am J Orthod Dentofacial Orthop. 2002 Jan;121(1):38-45 Problem solving in orthodontics- Burstone www.indiandentalacademy.com
  202. 202. Thank you For more details please visit www.indiandentalacademy.com www.indiandentalacademy.com

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